Судлаачид Төвдийн өндөр уулын мөсөн бүрхүүлээс дэлхийн цаг уурын түүхийг 100 мянга гаруй жилээр урагшлуулсан эртний мөсийг илрүүлсэн байна.
Төвдийн баруун хойд хэсгийн Гулия мөсөн бүрхүүлээс 1992 болон 2015 онд авсан мөсний голч дээжүүдэд хийсэн судалгаагаар тус бүс нутгийн цаг уурын бүртгэл 128,000 гаруй жилийн настай болохыг тогтоожээ. The Ohio State University-ийн эрдэмтдийн Science Advances сэтгүүлд нийтэлсэн энэхүү судалгаа нь уулын мөсөн голууд дэлхийн уур амьсгалын огцом өөрчлөлтийг хэрхэн даван туулж ирснийг харуулах шинэ асуултуудыг дэвшүүлж байна. Өмнөх судалгаануудад Гулиягийн мөсөн бүрхүүл нь зөвхөн дунд Холоцений үе хүртэлх түүхийг агуулдаг гэж үздэг байсан бол шинэ үр дүн нь мөсөн бүрхүүл илүү эртний түүхтэй болохыг баталлаа.
Эрдэм шинжилгээний багийг удирдсан Byrd Polar Research Center-ийн эрдэмтэн Лонни Томпсон 23 жилийн зайтай авсан дээжүүд химийн ижил төстэй шинж чанартай байгаа нь мөсөн бүрхүүл цаг уурын найдвартай мэдээллийг хадгалж ирснийг нотолж байна гэв. Судлаачид хүрээлэн буй орчны өөрчлөлтийг тодорхойлохдоо хүчилтөрөгчийн изотопын харьцааг ашигласан бөгөөд мөсний насыг тогтоохдоо берилли болон хлорын цацраг идэвхт изотопуудын задралын хурдад тулгуурлажээ. Энэхүү шинжилгээгээр 41,000 гаруй жилийн өмнө тохиолдсон дэлхийн соронзон орны өөрчлөлт болох Лашампын үзэгдлийн химийн мөр ул мөр олджээ.
Төвдийн агуйн ордууд болон мөсний дээжээс авсан мэдээллийг харьцуулснаар эрдэмтэд Гулиягийн мөсөн бүрхүүл нь сүүлчийн мөстлөгийн үе болон дулаарлын шилжилтийн үеийг хэрхэн давж гарсан цаг хугацааны нарийвчилсан хуваарийг гаргаж ирэв. Тус мөсөн бүрхүүл нь өндөр уулын байршил болон газарзүйн онцлогийн улмаас эртний мөсөн давхаргыг хадгалан үлдэх боломжтой байсан гэж үзэж байна. Энэхүү олдвор нь мөсөн голууд үүссэн цаг хугацаа болон байгалийн цаг уурын өөрчлөлтөд үзүүлсэн хариу үйлдлийг судлах урт хугацааны баримт болж байна.
Дэлгэрэнгүйг эх сурвалжаас харах
↓Эх сурвалжийг нээх ↓
High in the mountains of northwestern Tibet, an ancient ice cap has preserved something scientists are only beginning to understand. New research suggests that ice buried within it may be more than 128,000 years old, extending the region’s known climate record by over 100,000 years.
The discovery comes from the Guliya ice cap, where researchers examined ice cores collected during two separate expeditions in 1992 and 2015. Despite the 23-year gap, both sets of samples revealed remarkably similar chemical patterns.
According to The Ohio State University, the findings, published in Science Advances, raise new questions about how mountain glaciers survived dramatic climatic transitions. Earlier research suggested that the Guliya ice record extended only into the middle Holocene, making the newly identified ice considerably older than scientists previously believed.
A 23-Year Mystery Finally Uncovered
The research team, led by Lonnie Thompson, a professor of earth sciences and senior research scientist at the Byrd Polar Research Center, compared ice cores recovered from the Tibetan Plateau in 1992 and 2015.
“When did ice start forming on the planet and what did those natural processes of loss look like?” he said in a statement. “We need to know those things, and the only way you can really demonstrate it is with accurate time scales on these records.”
The scientists focused on oxygen isotopes, which provide information about past environmental changes. When they compared the two sets of measurements, they discovered striking similarities in their patterns. This correspondence suggested that the ice cap had preserved a reliable climate record despite the decades separating the drilling expeditions.
“Reproducibility of the records within a given ice cap is extremely important,” Thompson explained. “If you get an identical record a quarter of a century later, it can tell you a lot about the behavior of the ice over time.”
Thompson noted that ice cores recovered from Huascarán in Peru extend back more than 30,000 years, while the newly examined Tibetan samples could preserve a record reaching far deeper into Earth’s past.
An Ancient Magnetic Anomaly
To determine the age of the ice, researchers turned to radioactive isotopes of beryllium and chlorine. These naturally occurring isotopes decay at predictable rates, allowing scientists to identify events preserved in geological and environmental records.
Their analysis revealed evidence associated with the Laschamp geomagnetic excursion, a major disturbance in Earth’s magnetic field that occurred more than 41,000 years ago. This event left distinctive chemical signatures that researchers could use as chronological reference points.
The team then compared the ice-core findings with oxygen isotope records preserved in nearby Tibetan cave deposits. The agreement between these different sources helped scientists reconstruct a more reliable timeline for the Guliya ice.
In the study, the combined evidence suggests that the oldest ice may date back more than 128,000 years. This places the record well beyond the Holocene, which began nearly 12,000 years ago, and establishes Guliya as an unusually old mountain ice archive outside the polar regions.
What Kept Tibet’s Glaciers Alive for So Long?
The revised chronology carries implications for understanding how glaciers responded to major shifts in Earth’s climate. Previous interpretations suggested that the Guliya record reached back only to the middle Holocene, leaving uncertainty about whether ice from the last glacial period had survived.
The new evidence indicates that at least some of the Guliya ice cap persisted through the last ice age and the transition into the warmer Holocene. Its high elevation and surrounding terrain may have contributed to the preservation of these ancient deposits.
“If we only had Holocene-era ice in Tibet, that would mean that the big ice sheets from the last ice age didn’t persist through the early Holocene,” Thompson said. “But evidence shows that it did.”
The discovery also gives researchers a longer timeline for examining when glaciers formed, how long they persisted and how they responded to natural climatic changes. Scientists intend to analyze additional samples to determine how other environmental indicators fit into the newly established chronology.
“The big picture is that our results tell a very consistent story,” he explained. “If you get the science right, it’s consistent. It’s our understanding of what it’s trying to tell us that has to catch up.”
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